diff --git a/CQRS.Tests/TestsInfrasructure/ServiceLocator.cs b/CQRS.Tests/TestsInfrasructure/ServiceLocator.cs
index c77eb18ca..dec86d903 100644
--- a/CQRS.Tests/TestsInfrasructure/ServiceLocator.cs
+++ b/CQRS.Tests/TestsInfrasructure/ServiceLocator.cs
@@ -21,7 +21,7 @@ public void RegisterCommandHandler<TCommand, TCommandHandler>(TCommandHandler co
             where TCommand : IRequest
             where TCommandHandler : IRequestHandler<TCommand>
         {
-            Register(typeof(IRequestHandler<TCommand, Unit>), commandHandler, commandHandler);
+            Register(typeof(IRequestHandler<TCommand, Unit>), commandHandler);
             //Registration needed internally by MediatR
             Register(typeof(IEnumerable<IPipelineBehavior<TCommand, Unit>>), new List<IPipelineBehavior<TCommand, Unit>>());
         }
@@ -36,7 +36,7 @@ public void RegisterQueryHandler<TQuery, TResponse>(IRequestHandler<TQuery, TRes
 
         public IMediator GetMediator()
         {
-            return new Mediator(type => Get(type).Single());
+            return new Mediator(type => Get(type).First());
         }
     }
 }
diff --git a/MediatR.Tests/Sending/MoreThanOneHandler.cs b/MediatR.Tests/Sending/MoreThanOneHandler.cs
index e64deadb8..804ea7768 100644
--- a/MediatR.Tests/Sending/MoreThanOneHandler.cs
+++ b/MediatR.Tests/Sending/MoreThanOneHandler.cs
@@ -12,7 +12,7 @@ public class MoreThanOneHandler
     {
         public class ServiceLocator
         {
-            private readonly Dictionary<Type, List<object>> services = new Dictionary<Type, List<object>>();
+            private readonly Dictionary<Type, List<object>> services = new();
 
             public void Register(Type type, params object[] implementations)
                 => services.Add(type, implementations.ToList());
@@ -71,7 +71,7 @@ public MoreThanOneHandler()
             //Registration needed internally by MediatR
             serviceLocator.Register(typeof(IEnumerable<IPipelineBehavior<CreateIssueCommand, Unit>>), new List<IPipelineBehavior<CreateIssueCommand, Unit>>());
 
-            mediator = new Mediator(type => serviceLocator.Get(type).Single());
+            mediator = new Mediator(type => serviceLocator.Get(type).First());
         }
 
         [Fact]